The invention relates to a filling machine for filling a vessel with a liquid, and more particularly, to a filling machine provided with a liquid level adjusting controller which is capable of adjusting a liquid level or filling height in a vessel, that is, which is capable of adjusting the volume of a void which remains in the top of a vessel after it has been filled.
A filling machine generally comprises a rotatable tank containing a supply of a liquid to be filled, a plurality of filling heads disposed around the bottom of the tank toward the outer periphery at an equal circumferential spacing, and an elevatable vessel receptacle located below each head for placement of a vessel thereon. A conventional filling head comprises a liquid injection pipe which is disposed to be elevatable within the tank so that when it moves upward, it opens a liquid valve to allow a filling of a vessel with a liquid, a bottle mouth stuffing integrally elevatable with the injection pipe so as to be tightly engaged with the mouth of the vessel to seal it, and an exhaust pipe for externally exhausting an air from within the vessel when it is filled with a liquid.
In a filling machine constructed in the manner mentioned above, when the mouth of a vessel which is raised upward by means of the vessel receptacle tightly engages the bottle mouth stuffing to raise it, the liquid injection pipe which is integral with the bottle mouth stuffing is also forced upward, whereupon a liquid injection port (liquid valve) formed in the bottom of the exhaust pipe and an exhaust port (air valve) are opened to allow a filling of the vessel. The arrangement is such that the exhaust pipe is inserted into the vessel to a given depth so that when the liquid fills the vessel to the elevation of the exhaust port formed in the bottom of the exhaust pipe, the liquid to be filled rises inside the exhaust pipe to complete a filling operation when it reaches the liquid level within the tank. In this manner, a void or space is left within the vessel which corresponds to a difference in elevation between the mouth of the vessel and the location of the exhaust port of the exhaust pipe which is inserted into the vessel.
To change the volume of the void left within the vessel, the depth to which the exhaust pipe is inserted into the vessel may be changed. In other words, it is only necessary that a relative position between the bottle mouth stuffing which tightly engages the mouth of the vessel and moves upward together with the vessel, and the exhaust pipe be changed. Such a liquid level adjusting controller for a filling machine has already been proposed. For example, see Japanese Laid-Open Utility Model Application No. 8998/1987 where the relative position between the exhaust pipe and the bottle mouth stuffing is changed by manually changing a spacer or Japanese Laid-Open Utility Model Application No. 43500/1991 where the connection between the bottle mouth stuffing and the liquid injection pipe is disengaged by a manual operation, the tank is elevated, a cleaning cup is utilized to raise the bottle mouth stuffing through a given stroke, and then the bottle mouth stuffing and the liquid injection pipe are locked together again.
A conventional liquid level adjusting controller as mentioned above is either manual or semi-automatic in operation, and thus requires a manual operation, which is troublesome and time consuming. In addition, a known controller only permits a stepwise change among predetermined elevations, but fails to provide a stepless adjustment. The present applicant has previously proposed a liquid level adjusting controller which enables a stepless adjustment to be made automatically (see Japanese Utility Model Application No. 117390/1990). In this liquid level adjusting controller, an air lock mechanism is released and the connection between the liquid injection pipe and the bottle mouth stuffing is disengaged. Subsequently, a cleaning cup is inserted between the bottle mouth stuffing and the vessel receptacle which is located therebelow. The tank which contains a supply of a filling liquid is then lowered to cause the bottle mouth stuffing to be forced up by means of the cleaning cup, thereby changing the elevation of the bottle mouth stuffing relative to the exhaust pipe which is secured to the tank. The air lock mechanism is then again operated to lock such relative elevation.
The automatic liquid level adjusting controller thus constructed eliminates the need for a manual operation to improve the working efficiency, but still requires a withdrawal of the cleaning cup. In addition, if it is found necessary, during the operation of the filling machine, to change the volume of the void by a small amount, such change cannot be achieved in a simple manner.
In the filling machine constructed as mentioned above, the arrangement is made such that when the liquid filling the vessel reaches the exhaust port of the exhaust pipe and then rises within the exhaust pipe until it reaches the liquid level within the tank to complete a filling operation, the liquid valve and the air valve are closed under this condition. Accordingly, a residue of the filling liquid remains within the exhaust pipe upon completion of the filling operation. Accordingly, when the liquid valve and the air valve are opened for the next time the filling operation takes place, an exhaust passage within the exhaust pipe remains blocked, and accordingly a filling of the liquid cannot take place until such residue is discharged and the exhaust passage recovers its intended function. In addition, if the filling operation takes place, the flow rate is greatly retarded.
To accommodate for this, a filling machine has already been proposed (see Japanese Patent Publication No. 52914/1983) which is provided with a negative pressure chamber which causes a negative pressure to be produced in the top of the exhaust pipe so that a channel path be secured for the air which is exhausted from within the vessel during a filling operation, by discharging the residue of liquid which remains within the exhaust pipe at the commencement of the filling operation or if such discharge cannot be assured completely, by disrupting a stabilized condition for the residue of liquid within the exhaust pipe. The negative pressure chamber is defined by a plunger which is secured to the liquid injection pipe and which is slidably and tightly fitted in the top end of the exhaust pipe. When the plunger moves upward together with the liquid injection pipe, the volume within the exhaust pipe increases to produce a negative pressure, and as the plunger rises further upward, a communication is established between the top space within the exhaust pipe and a top space within the tank, withdrawing the filling liquid which remains within the liquid pump for discharge into the tank.
The described arrangement for discharging a residue of liquid which remains within the exhaust pipe for a filling machine constructed in the manner mentioned above involves difficulties causes by the use of the plunger in that it is unfavorable in sanitary respect and disadvantageous in cost considerations.